title: Density dependent elevation of phosphatidylinositol-3 kinase level in rat 3Y1 cells.
abstract: We have explored the levels of phosphatidylinositol-3 kinase protein during culture of rat 3Y1 cells. Confluent cell cultures exhibited a higher level of phosphatidylinositol-3 kinase compared with that of growing cells. After replating of the cells on fresh dishes, the level of phosphatidylinositol-3 kinase returned to that of growing cells within 24h. This density-dependent regulation of the phosphatidylinositol-3 kinase level was not lined to cell growth, because growth arrest by serum starvation did not cause elevation of the phosphatidylinositol-3 kinase level. Northern blotting analysis revealed that this regulation was based on the transcriptional level. After cell growth was arrested by contact inhibition, elevation of the level of phosphatidylinositol-3,4,5-trisphosphate was detected suggesting that phosphatidylinositol-3 kinase was activated in these cells. These effects were not seen in src-transformed 3Y1 cells, suggesting that this regulation was lost in transformed cells.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Science, University of Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Daduang
authors.forename: K
authors.initials: K
authors.lastname: Kimura
authors.forename: S
authors.initials: S
authors.lastname: Nagata
authors.forename: Y
authors.initials: Y
authors.lastname: Fukui
mesh_terms: D000818:Animals; D002452:Cell Count; D002455:Cell Division; D002460:Cell Line; D002461:Cell Line, Transformed; D003260:Contact Inhibition / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology*; D016391:Genes, src; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D018129:Phosphatidylinositol Phosphates; D012333:RNA, Messenger; C060974:phosphatidylinositol 3,4,5-triphosphate; D019869:Phosphatidylinositol 3-Kinases